世界最冷的物质排名（世界上最冷的物质有多冷）

世界最冷的物质排名（世界上最冷的物质有多冷）That’s 395 million times colder than your refrigerator 100 million times colder than liquid nitrogen and 4 million times colder than outer space.只有比绝对零度高一点点的一团气体They’re in physics labs:是在物理实验室里clouds of gases held just fractions of a degree above absolute zero.

The coldest materials in the world aren’t in Antarctica.

全世界最冷的東西不是在南極

They’re not at the top of Mount Everest or buried in a glacier.

也不是在珠穆朗玛峰上更不是被埋在冰河里

They’re in physics labs:

是在物理实验室里

clouds of gases held just fractions of a degree above absolute zero.

只有比绝对零度高一点点的一团气体

That’s 395 million times colder than your refrigerator 100 million times colder than liquid nitrogen and 4 million times colder than outer space.

那比你的冰箱还要冷 3.95 亿倍，比液态氮还冷 1 亿倍，比外太空的温度还低了 400 万倍。

Temperatures this low give scientists a window into the inner workings of matter and allow engineers to build incredibly sensitive instruments that tell us more about everything from our exact position on the planet to what’s happening in the farthest reaches of the universe.

如此低温的温度给科学家一个窗口来探讨物质内部的运作，也让工程师们可以制造出极为敏感的仪器，好让我们知道更多资讯，关于我们在地球上所在的位置，一直到离我们最远的宇宙所发生的事。

How do we create such extreme temperatures?

我们要如何创造如此低温呢？

In short by slowing down moving particles.

简单来说，就是把移动中的粒子的速度减缓

When we’re talking about temperature what we’re really talking about is MOTion.

当我们讲到温度时，我们在说的其实是运动

The atoms that make up solids liquids and gases are moving all the time.

固体是由原子组成，而液体和气体则不停地在运动

When atoms are moving more rapidly we perceive that matter as hot.

当原子快速移动时，我们会感觉到热

When they’re moving more slowly we perceive it as cold.

当原子移动缓慢时，我们接受到冷

To make a hot object or gas cold in everyday life we place it in a colder environment like a refrigerator.

生活中，如果要将一个物体或液体变冷的话我们会把它们放到一个相对冷的环境，像是冰箱

Some of the atomic motion in the hot object is transferred to the surroundings and it cools down.

有些在热的物体里的原子会转移到环境当中进而使物体冷却

But there’s a limit to this: even outer space is too warm to create ultra-low temperatures.

但这样的冷却还是有极限的要创造极度低温，连外太空的环境都太热

So instead scientists figured out a way to slow the atoms down directly – with a laser beam.

所以呢，科学家想出了一个办法能够直接使原子减速使用雷射光

Under most circumstances the energy in a laser beam heats things up.

在大部分的情况下雷射光会加热物体

But used in a very precise way the beam’s momentum can stall moving atoms cooling them down.

但如果使用得很精准的话雷射光可以使移动中的原子减速，进而降低温度

That’s what happens in a device called a magneto-optical trap.

这就是磁光陷阱 (MOT) 的运作原理

Atoms are injected into a vacuum chamber and a magnetic field draws them towards the center.

原子被注入真空的空间中而磁场会把它吸引到正中间

A laser beam aimed at the middle of the chamber is tuned to just the right frequency that an atom moving towards it will absorb a photon of the laser beam and slow down.

镭射光会瞄准空间中的正中心调到正确的频率，这样就能使移动中的原子吸收雷射光的光子，然后减缓速度

The slow down effect comes from the transfer of momentum between the atom and the photon.

这个减速的效果来自动力的转变介于原子与光子之间

A total of six beams in a perpendicular arrangement ensure that atoms traveling in all directions will be intercepted.

六条垂直排列的光束确保移动的原子都会被拦截下来

At the center where the beams intersect the atoms move sluggishly as if trapped in a thick liquid — an effect the researchers who invented it described as “optical molasses.”

在正中间，也就是光束的交界处，原子的移动会变得很迟缓，就像是被困在黏稠的液体中发明这个方法的人称之为「蜜糖光学」

A magneto-optical trap like this can cool atoms down to just a few microkelvins — about -273 degrees Celsius.

这样的磁光陷阱，可以把原子冷却至绝对温标大约是负 273 度摄氏。

This technique was developed in the 1980s and the scientists who'd contributed to it won the Nobel Prize in Physics in 1997 for the discovery.

这项技术在 1980 年代被开发而有贡献的科学家们在 1997 年赢得了诺贝尔物理学奖

Since then laser cooling has been improved to reach even lower temperatures.

从此之后，雷射冷却就一直经过改良，可以达到更低的温度

But why would you want to cool atoms down that much?

但是为什么要冷却原子到如此低温呢？

First of all cold atoms can make very good detectors.

首先，低温的原子可以当一个很好的侦测者

With so little energy they’re incredibly sensitive to fluctuations in the environment.

有着极低的能量他们对于环境中的波动是异常的敏感

So they’re used in devices that find underground oil and mineral deposits and they also make highly accurate atomic clocks like the ones used in global positioning satellites.

所以他们会被用在找寻地底的石油及矿物的仪器上，而糗他们也是非常精准的原子钟，像是用于全球定位的卫星当中。

Secondly cold atoms hold enormous potential for probing the frontiers of physics.

再者，低温的原子有着极大的潜能，来探测尚未被开发的物理学

Their extreme sensitivity makes them candidates to be used to detect gravitational waves in future space-based detectors.

他们极佳的敏锐性使他们成为，在未来太空中引力探测器的绝佳候选人。

They’re also useful for the study of atomic and subatomic phenomena which requires measuring incredibly tiny fluctuations in the energy of atoms.

他们在原子与次原子的现象研究中有绝佳的帮助，因为这类研究需要测量原子中极微小的能量波动

Those are drowned out at normal temperatures when atoms speed around at hundreds of meters per second.

这些波动在正常的温度下是看不出来的，尤其是当原子的速度达到每秒 100 公尺时

Laser cooling can slow atoms to just a few centimeters per second — enough for the motion caused by atomic quantum effects to become obvious.

雷射冷却可以把原子的速度降到每秒只有几公分，这足够使原子量所形成的运动变得显而易见。

Ultracold atoms have already allowed scientists to study phenomena like Bose-Einstein condensation in which atoms are cooled almost to absolute zero and become a rare new state of matter.

极度低温的原子已经让科学家能够研究像是玻色-爱因斯坦凝聚，原子被降到几乎绝对零度进而变成一个全新的物质

So as researchers continue in their quest to understand the laws of physics and unravel the mysteries of the universe they’ll do so with the help of the very coldest atoms in it.

只要研究人员持续在物理学中调查和解开宇宙的奥妙，他们还是会继续受到极度低温原子的帮助。